Silver halide color photographic element containing a magenta color coupler and a carboxy substituted thiazoline compound

ABSTRACT

LIGHT SENSITIVE PHOTOGRAPHIC ELEMENTS COMPRISING SURFACE SENSITIZED CONVERTED-HALIDE SILVER HALIDE GRAINS ARE CONTAINED IN EMULSIONS WHICH ARE PARTICULARLY AND EFFECTIVELY STABILIZED BY ADDENDA WHICH RESIST PRE-PROCESSING DETERIORATION, POST-PROCESSING DYE STABILITY AND UNWANTED SHIFTING IN COLOR BALANCE. PREFERRED SUCH ADDENDA ARE CARBOXY SUBSTITUTED THIAZOLINETHIONE AND CARBOXY SUBSTITUTED THIAZOLIDINES.

United States Patent US. Cl. 96-74 Claims ABSTRACT OF THE DISCLOSURELight sensitive photographic elements comprising surface sensitizedconverted-halide silver halide grains are contained in emulsions whichare particularly and effectively stabilized by. addenda which resistpre-processing deterioration, post-processing dye stability and unwantedshifting in color balance. Preferred such addenda are carboxysubstituted thiazolinethione and carboxy substituted thiazolidines.

This is a continuation-in-part of applicants copending application Ser.No. 21,468 filed Mar. 20, 1970, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to photographic materials, their preparation and use. In oneaspect, this invention relates to a photographic element comprisingconverted-halide silver halide grains whose optical density curve shapeis stabilized by the addition of a carboxy-substituted com pound. Inanother aspect, this invention relates to multilayer, multicolorphotographic elements to which is added stabilizing addenda in order toprovide true color balance.

DESCRIPTION OF THE PRIOR ART Photographic elements comprising lightsensitive silver halide grains are subject to a wide variety of factorswhich can adversely affect their ability to faithfully reproduce animage after exposure and processing. For example, fog, the more or lessintense blackening of silver halide, can be caused by prolongeddevelopment, aerial oxidation, ageing and other physical factorsincluding light reflection on lens surfaces. Speed losses or decreasesin the sensitivity of the silver halide grain can be caused by a varietyof factors including the addition of addenda which adversely affect thesensitometric characteristics of the grain and the element. When thesensitivity of halide grains is thus adversely affected, the density inthe toe of the characteristic curve shape is changed. Incolor-containing elements this change substantially disrupts the colorbalance and leads to untrue colors in the reproduced image. Inphotographic elements and particularly multilayer color elements, thevariation of light intensity or exposure time not only changes effectivefilm speed and contrast but usually results in a shift in color balancedue to the differences in reciprocity effect in each of thecolorcontaining layers.

Differences of toe softness or sharpness of the charac teristic curveare of great importance. A sharper toe tends to produce whiter whites,and brighter highlights, while a softer toe tends to distort and shiftcolor balance. For example, a soft magenta toe produces unnatural anddispleasing red or pink rather than white objects, such as clouds. Aslittle as a 0.02 change in the toe density areas is far more criticalthan a 0.10 change in density in the maximum density areas. While thehuman eye can see slight changes in loW density areas much easier thanin areas of high color saturation, shifts in green maximum saturationcan be perceived by the eye more readily than red or blue shifts, sincethe eye is most sensitive to green.

In the past, attempts to improve the appearance of the printedphotographic image have included adding optical brightening agents orfluorescent agents to enhance the white or highlighted areas, such asset forth in US. Pat. 3,416,923 of VanCampen et al. issued Dec. 17,1968.

Converted-halide silver halide grains have been found particularlyeffective in providing certain improved light sensitive silverhalide-containing elements and emulsions, such as taught by Davey andKnott in US. Pat. 2,592,250 issued Apr. 8, 1952, but nowhere have suchemulsions overcome the problems solved by the present inventionincluding preprocess keeping and post process dye stability.

The incorporation into developer solutions of certain thiazoles indeveloping coarse grain silver halide radiographic emulsions is knownfrom US. Pat. 3,306,746 issued Feb. 28, 1967 to Schwartz. et al.Further, various compounds such as triazoles, imidazoles,benzimidazoles, triazines and the like are described as satisfactoryantifoggants for photographic elements in U.S. Pat. 2,819,965 issuedJan. 14, 1958 to Murray et al.

However, nowhere heretofore has there been any teaching that byincorporating the carboxy-substituted compounds disclosed herein in thephotographic elements described, highly desirable and previouslyunattainable results are achieved. For even where known compounds suchas the antifoggants described above have been successfully used instabilizing the emulsion against fog, there appears to have been littleor no effect upon improving either the curve shape of said emulsion, thepreprocess keeping or the post process-dye stability.

It is, therefore, evident that the art would be enhanced by photographicelements and improved silver halide grains and emulsion systems whichnot only exhibit reduced fog but also possess increased speed, increasedstability on keeping, better reciprocity characteristics and high levelof color reproduction integrity after processing.

Accordingly, it is an object of this invention to provide photographicmaterials which exhibit improved combinations of sensitometricproperties.

Another object of this invention is to provide photographic elements andlayers, and particularly multilayers such as color-forming layers, whichexhibit increased contrast and decreased shifting or color balance.

Still another object of this invention is to provide improvedphotographic elements comprising surfacesensitized converted-halidesilver halide grains in combination with a carboxy-substitutedthiazolinethione or thiazolidine whereby deviations in thecharacteristic sensitometric curve shape are controlled, i.e. effectedin a desirable manner within tolerable limits.

Still other objects will become apparent to those skilled in the artfrom a consideration of the following examples, specification andclaims.

SUMMARY OF THE lNVENTION In accordance with this invention, there is nowprovided a photographic element comprising a support, surface sensitizedconverted-halide silver halide grains and a carboxy-substitutedthiazolinethione or thiazolidine. In a preferred embodiment thecarboxy-substituted thiazolinethione or thiazolidine is present in theelement in a concentration suflicient to control the characteristic,i.e. the optical density curve shape of said silver halide grains suchas to maintain the color balance, preprocess keeping and post processdye stability. The element can suitably in which R is hydrogen,carboxymethyl or each R is alkyl preferably lower alkyl of 1 to carbonatoms such as methyl, ethyl, propyl, butyl, pentyl and the like, when Ris other than hydrogen or is carboxy methyl and each R is hydrogen orcarboxyl and wherein at least one of the radicals R R and R comprises acarboxyl group or a carboxymethyl group; or

in which R is hydrogen or acyl such as formyl and the like, R ishydrogen or methyl and R is hydrogen, car boxyl, alkyl such as from 1 to8 carbon atoms and preferably up to 6 carbon atoms such as methyl,ethyl, pentyl, hexyl, and the like.

These compounds are unexpectedly useful in achieving the purposes setforth herein and are prepared by techniques well known in the art. Forexample, general methods of preparation of compounds in Groups ('I) or(II) have been previously reported and the methods for preparing saidcompounds are well known. In particular, 4-thiazoline-2-thiones, theirintermediates and derivatives are prepared conveniently by the methodsdisclosed in J. Org. Chem. vol. 29, pp. 2l462l50 Humphlett and Lamon(1964) which respectively employs the reaction ofammoniumdithiocarbamate and a-halo aldehydes or ketones and the reactionof ammonium dithiocarbamate and 1-alkylsulfonyl-3-bromo-2-propanones.

The compounds represented by structural Formula II can be convenientlyprepared by the methods disclosed in preparing thiazolidines by aqueouscalcium hydroxide decomposition of lanthionine as set forth fully in J.Am. Chem. Soc. 79, 1644 (1957) Damn et a1. Exemplary of such compoundsinclude 4-thiazolidine carboxylic acid 2-hexyl-4-thiazolidine carboxylicacid 2-methyl-2,4-thiazolidine dicarboxylic acid and3-formyl-2,2-dimethyl-4-thiazolidine carboxylic acid.

By the practice of the present invention, an unexpected, highlydesirable and significant stabilization of photographic elements is nowachieved whereby preprocess keeping, post process dye stability anddensity curve shape control are improved. These improvements are madepossible by combining with said grains an heterocycliccarboxy-substituted compound, such as for example, a carboxy-substitutedthiazolinethione or thiazolidine and in a preferred embodiment acompound such as 4-carboxymethyl-4-thiazoline-2-thione.

As will be understood by those skilled in the art, the presence of saidcharacteristic curve-shape control addenda can be effected in a numberof ways, such as by the direct incorporation of any of the above classof compounds or by their immediate or mediate precursors.

4 For example, it has been found to be particularly useful to utilize[5,4 (l,2-D-gluco)-thiazolyl]-disulfide which when cleaved, functions as2-thiones and is only one example of 4-thiazoline-2-thione precursor.

The light sensitive photographic silver halide emulsions, layers andelements disclosed in utilizing the present invention featureconverted-halide silver halide grains in which the halide comprises atleast about 50 mole percent bromide and up to about 10 mole percentiodide, any remaining halide being chloride. Preferentially somechloride should be present and it can vary within the limits disclosedthat is an upper limit of about 50 mole percent down to a lesser amountpresent and preferably 12 to 15 percent chloride. The surface of saidgrains are chemically sensitized by a variety of sensitizers well knownin the art such as is set forth more fully hereafter.

In accordance with one embodiment of this invention the grains thusdescribed are present in a photographic layer containing a color formingcoupler. Particularly good results are obtained with silver halidegrains containing about mole percent bromide and about 10 mole percentchloride.

The term converted-halide silver halide grains as employed herein iswell known to those skilled in the art and denotes silver halide grainswhich are prepared in a variety of ways, one such way is by firstforming an emulsion or dispersion of silver salt grains consisting atleast in part of a silver salt more soluble in water than silverbromide, and then converting at least a portion of said salt grains tosilver bromide or bromoiodide salts.

More specifically in one preferred method said silver halide grains canbe prepared by forming a silver salt which is (1) more soluble in waterthan silver bromide, and (2) has a solubility of less than about 0.02grams, and perferably less than about 0.00002 gram per milliliters ofwater at 20 C. Useful silver salts more soluble than silver bromideinclude silver chloride, silver thiocyanate and silver citrate and thelike. Such salts are conveniently formed, for example, by addingseparate solutions of silver nitrate in water and a suitable aqueousalkali metal salt solution, such as potassium chloride, potassiumcitrate or potassium thiocyanate and the like respectively to an aqueousgelatin-containing solution containing a small amount of the alkalimetal salt. The first two solutions are preferably added slowly to theaqueous gelatin-containing solution while maintaining the temperature ofall the solutions between about 20 and 50 C. After the formation of thesilver salts more soluble than silver bromide, a suitable bromide saltcan be added to convert at least part of the more soluble silver salt tosilver bromide. If desired, a suitable iodide salt can also be added toform silver bromoiodide. Potassium bromide and potassium iodide areespecially useful for this purpose. When silver chloride is used as thesilver salt more soluble than silver bromide, it is not necessary toconvert all the chloride to bromide or bromoiodide, nor is it necessarythat the silver halide grains contain iodide. One method for preparingemulsions of the general type employed in this invention is more fullydescribed by Davey and Knott, U.S. Pat. 2,592,250 issued Apr. 8, 1952.

The converted-halide silver halide emulsions described herein have alsobeen referred to by those skilled in the art as halide conversionemulsions and halide converted photographic emulsions.

The characteristic curve shape of a photographic silver halide emulsionis generally S-shaped with a straight part between the two regions ofunderexposure and overexposure. This curve is well known to thoseskilled in the art as the H and D curve or the D log E curve. It resultsfrom the particular properties of the various grains and photographicreproduction of the image becomes more exact when the toe of the curveis sharpened to the benefit of the central straight part. Thus, wherethe true color balance of the red, blue and green curves is essential asin color photography, these three characteristic curves must besubstantially superimposable at all points. An increase or decrease incontrast such as those which result in softening the toe, also resultsin unacceptable color balance.

As dramatically shown by the data in the following tables where the toeof the curve is soft, and particularly in the green curve, the colorbalance of highlight areas is shifted so that an undesirable generalreddish-pink color is observed. By practicing this invention, the curvetoe is unexpectedly maintained providing heretofore unattainable colorbalanced highlights.

In still another preferred embodiment, the halide of the silver halidegrains present in the photographic element of this invention comprise atleast about 50 mole percent bromide and up to about mole percent iodide,any remaining halide being chloride and the surface of said grains beingchemically sensitized and the like.

The converted-halide silver halide grains employed in this invention arechemically sensitized by any means suitable for this purpose, manymethods having been previously described in the prior art. Chemicalsensitization is a surface phenomenon and as used herein, includessensitization of the type described by Antoine Hautot and HenriSauvenier in Science et Industries Photographiques," vol. XXVIII,January 1957, pages 1-23 and January 1957, pages 57-65. This chemical,i.e. surface sensitization includes three major classes, viz., gold ornoble metal sensitization, sulfur sensitization, such as by a labilesulfur compound, and reduction sensitization, i.e., treatment of thesilver halide with a strong reducing agent which does not fogappreciably the silver halide but introduces small specks of metallicsilver into the silver halide crystal or grain.

The converted-halide silver halide grains can likewise be chemicallysensitized by any of the accepted procedures. Emulsions containing suchgrains can be digested with naturally active gelatin, or compounds ofthe sulfur group can be added, such as those described in Sheppard US.Pat. 1,574,944 issued Mar. 2, 1926, Sheppard et al. US. Pat. 1,623,499issued Apr. 5, 1927, and Sheppard et al. US. Pat. 2,410,689 issued Nov.5, 1946. Particularly good results are obtained with sulfur, selenium,tellurium sensitizers and the like.

The converted-halide silver halide grains can also be treated with saltsof the noble metals, such as ruthenium, rhodium, palladium, iridium, andplatinum. Representative compounds are ammonium chloropalladate,potassium chloroplatinate, and sodium chloropalladite, which are usedfor sensitizing in amounts below that which produces any substantial foginhibition, as described in Smith and Trivelli US. Pat. 2,448,060 issuedAug. 31, 1948, and as antifoggants in high amounts, as described inTrivelli and Smith US. Pats. 2,566,245 issued Aug. 28, 1951 and2,566,263 issued Aug. 28, 1951.

The converted-halide silver halide grains can also be chemicallysensitized with gold salts as described in Waller et al., U.S. Pat.2,399,083 issued Apr. 23, 1946 and Damschroder et al., US. Pat.2,642,361 issued June 16, 1953. Suitable compounds are potassiumchloroaurite, potassium aurithiocyanate, potassium chloroaurate, aurictrichloride and 2-aurosulfobenzothiazole methochloride.

The converted-halide silver halide grains can also be reductionsensitized with reducing agents. such as stannous salts (Carroll US.Pat. 2,487,850 issued Nov. 15, 1949), polyamines, such as diethylenetriamine (Lowe and Jones U.S. Pat. 2,518,698 issued Aug. 15, 1950),polyamines, such as spermine (Lowe and Allen US. Pat. 2,521,925 issuedSept. 12, 1950), or bis(B-aminoethyl) sulfide and its water-solublesalts (Lowe and Jones US. Pat. 2,521,926, issued Sept. 12, 1950).

A wide variety of photographic color couplers can be employed in thepractice of this invention. As used herein, the term color coupler orcolor-forming dye couplers includes any compound which reacts (orcouples) with the oxidation products of primary aromatic aminodeveloping agent on photographic development to form a dye. Typicaluseful color couplers include phenolic, S-pyrazolon, heterocyclic andopen-chain ketomethylene compounds. Specific cyan, magenta and yellowcolor couplers which can be used, respectively, in the cyan, magenta,and yellow dye-forming units of the invention are described in Graham etal. US. Pat. 3,046,129 issued July 24, 1962, column 15, line 45 throughcolumn 18, line 51, which disclosure is incorporated herein byreference. Other suitable couplers are described in Salminen et al. US.Pat. 2,423,730 issued IJuly 8, 1947; Loria et al. US. Pat. 2,600,788issued June 17, 1952; De Maria U.S. Pat. 2,875,051 issued Feb. 24, 1959;Bush et al. US. Pat. 2,908,573 issued Oct. 13, 1959; Weissberger et al.US. Pat. 3,265,506 issued Aug. 9, 1966; Greenhalgh et al. US. Pat.3,127,269 issued Mar. 31, 1964; Loria US. Pat. 3,408,194 issued Oct. 29,1968 and Lestina Belgian Pat. 698,354. Such color forming couplers canbe dispersed in the emulsion layers in any convenient manner, such as byusing the solvents and the techniques described in Jelley and Vittum US.Pat. 2,322,027 issued June 15, 1943 or Fierke and Chechak US. Pat.2,801,171 issued July 30, 1957. The useful couplers include Fischer-typeincorporated couplers such as those disclosed in Fischer US. Pat.1,055,155 issued Mar. 4, 1913, and particularly non-ditfusibleFischer-type couplers containing branched carbon chains, e.g., thosereferred to in the references cited in Frohlich et al. US. Pat.2,376,679, issued May 22, 1945, column 2, lines 5060. These elements canbe processed by one of the procedures described in Graham et al. US.Pat. 3,046,129 issued July 24, 1962, columns 23 and 24, or by thedevelopment process described by Edens et al. US. patent applicationSer. No. 736,010 filed June 11, 1968 and corresponding German patentapplication 1,928,554 which features a color process in which the colordevelopment step is followed with a blix bath comprising silver halidesolvent and an oxidizing agent for silver. The disclosure of the Edenset al. application is incorporated herein by reference.

The photographic color forming couplers employed in this invention canbe positioned in photographic elements so that during processing inaqueous alkaline color developing solutions, color developing agentoxidized on developing silver halide in the photographic element reactswith the photographic color coupler. Accordingly, the photographic colorcouplers can be integral with and contiguous to the silver halide bybeing incorporated in the silver halide emulsion or in a separate layerc0ntiguous thereto. Also, the photographic color couplers can beseparated from silver halide emulsion layers by layers of a hydrophiliccolloid such as gelatin or a related composition through which oxidizeddeveloping agents can really diffuse in the presence of an aqueousalkaline processing solution.

In color systems of the type useful in this invention, subtractive dyeimages can be generated by a color negative process, such as the processdescribed by W. T. Hanson and W. I. Kesner in an article in the Journalof the Society of Motion Picture and Television Engineers, vol. 61(1953) pages 667-701; or, by a color reversal process wherein reversalsilver images are generated from a photographic color coupler, such asby using a direct positive emulsion or using a negative emulsion whichis giveman imagewise exposure, developed in a black-andwhite developerto provide a negative silver image, and then at least one additionalexposure (or other suitable fogging treatment) followed by additionaldevelopment to generate the desired subtractively colored dye images.

In preferred embodiments of the invention, the photographic elementincludes a hydrophilic colloid layer which contains a suitableultraviolet absorber, many of which are well known to those skilled inthe art, for example, those including the benzotriazoles and moreparticularly the phenyl-type compounds described in Sawdey U.S.

Pat. 3,253,921 issued May 31, 1966 and the thiazolidines of the typedescribed in a number of Sawdey U.S. Pats. 2,739,971 issued Mar. 27,1956, 2,739,888 issued Mar. 27, 1956 and 3,250,617 issued May 10, 1966and others. This layer can be an overcoat or can be positioned betweenthe redand green-sensitive emulsion layers in elements having a supportcoated, in the order given, with blue, greenand red-sensitive emulsionlayers.

The multilayer color-producing elements of the invention preferablycomprise blue-, greenand red-sensitive silver halide emulsion layers. Asis well known, silver halide emulsions are typically sensitive to blueradiation, although additional sensitizing dyes absorbing in the blueregion can also be added to modify the sensitivity of the emulsion toblue radiation as desired. Green and red spectral sensitization can beconferred by any of the dyes suggested in the art for this purpose,including those described in Brooker et al. US. Pat. 2,526,632 issuedOct. 24, 1950; Sprague U.S. Pat. 2,503,776 issued Apr. 11, 1950; Brookeret al. US. Pat. 2,493,748 issued Jan. 10, 1950; and Taber et al. US.Pat. 3,384,486 issued May 21, 1968. Spectral sensitizers which can beused include the cyanines, merocyanines, complex (tri or tetranuclear)merocyanines, complex (tri or tetranuclear) cyanines, holopolarcyanines, styryls, hemicyanines (e.g. enamine hemicyanines), oxonols andhemioxonols. Dyes of the cyanine classes may contain such basic nucleias the thiazolines, oxazolines, pyrrolines, pyridines, oxazoles,thiazoles, selenazoles and imidazoles. Such nuclei may contain alkyl,alkylene, hydroxyalkyl, sulfoalkyl, carboxyalkyl, aminoalkyl and enaminegroups and may be fused to carbocyclic or heterocyclic ring systemseither unsubstituted or substituted with halogen, phenyl, alkyl,haloalkyl, cyano, or alkoxy groups. The dyes may be symmetrical orunsymmetrical and may contain alkyl, phenyl, enamine or heterocyclicsubstitutents on the methine or polymethine chain. The merocyanine dyesmay contain the basic nuclei mentioned above as Well as acid nuclei suchas thiohydantoins, rhodanines, oxazolidendiones, thiazolidenediones,barbituric acids, thiazolineones, and malononitrile. These acid nucleimay be substituted with alkyl, alkylene, phenyl, carboxyalkyl,sulfoalkyl, hydroxyalkyl, alkoxyalkyl, alkylamino groups, orheterocyclic nuclei. Combinations of these dyes may be used, if desired.In addition, supersensitizing addenda which do not absorb visible lightmay be included, for instance, ascrobic acid derivatives, azaindenes,cadmium salts, and organic sulfonic acids as described in McFall et al.US. Pat. 2,933,- 390 issued Apr. 19, 1960 and Jones et al. US. Pat.2,937,- 089 issued May 17, 1960. The multilayer photographic elements ofthe invention can be spectrally sensitized, and contain the filterlayers described by Schwan et al. US. Pat. application Ser. No. 715,005filed Mar. 21, 1968 and corresponding Belgian Pat. 729,204 of Aug. 28,1969, and Schwan et al. continuation-in-part application Ser. No.864,275 filed Sept. 29, 1969.

Spectral sensitizing dyes can be added to the emulsions in anyconvenient manner, such as by treating the emulsion with a solution of asensitizing dye in an organic solvent or the dye may be added in theform of a dispersion as described in Owens et al. British Pat. 1,154,781of June 11, 1969. For optimum results, the dye may either be added tothe emulsion as a final step or at some earlier stage.

These silver halide grains can be present in the element in anyconvenient fashion such as in one or more layers which are themselvesdeposited by vacuum or laid-down in emulsion form for example.

As will be more fully set forth by examples which follow, a preferredphotographic element of this invention can provide a multicolor imageand in such elements, the curve-shape-controlling addenda are mosteffectively contained in at least one hydrophilic colloid-containinglayer, such as a gelatin layer. Where the supported element has coatedthereon at least three superimposed hyydrophilic colloid layerscontaining color-forming dye couplers sensitive to red, green and blueradiation; particularly good and unexpected results are obtained whenthe carboxysubstituted thiazolinethione or thiazolidine is contained inthe layer having the green radiation sensitive color forming dyecoupler. In such cases, the effective concentration varies from about 50to about 500 mg./mole of silver based upon the total converted-halidesilver halide grains.

Particularly good results are obtained where this invention is embodiedin an element having a white reflecting support bearing layerscomprising the converted-halide silver halide grains above described.These layers are separate and are radiation sensitive respectively toblue, green and red, said layers containing color-forming dye couplerscapable of forming respectively, yellow, magenta, and cyan dyes uponcolor development. The red-sensitive layer containing the cyan-formingcoupler is preferably the outermost light sensitive layer and cancontain in a preferred aspect the above described fluorescent agent inthe solvent. In another preferred embodiment of this invention, theblue-sensitive layer can be effectively disposed adjacent the reflectingsupport. It is understood that various subbing, binding or otherintermediate layers can be placed between, over and under thesecoupler-containing layers with equally good results.

The halide conversion silver halide grains used with this invention maybe combined with speed increasing compounds such as polyalkyleneglycols, cationic surface active agents and thioethers or combinationsof these as described in Piper US. Pat. 2,886,437 issued May 12, 1959;Dann et al. US. Pat. 3,046,134 issued July 24, 1962; Carroll et al., US.Pat. 2,944,900 issued July 12, 1960; and Gotfe US. Pat. 3,294,540 issuedDec. 27, 1966.

The halide conversion silver halide grains used in the practice of thisinvention can be protected against the production of fog and can befurther stabilized against loss of sensitivity during keeping. Suitableantifoggants and stabilizers each used alone or in combination includethiazolium salts described in Brooker et al., US. Pat. 2,131,038 isuedSept. 27, 1938 and Allen et al., US. Pat. 2,694,716 issued Nov. 16,1954; the azaindenes described in Piper US. Pat. 2,886,437 issued May12, 1959, and Heimbach et al., US. Pat. 2,444,605 issued July 6, 1948;the mercury salts as described in Allen et al. US. Pat. 2,728,663 issuedDec. 27, 1955; the urazoles described in Anderson et al., U.S. Pat.3,287,135 issued Nov. 22, 1966; the sulfocatechols described in Kennardet al. US. Pat. 3,236,652 issued Feb. 22, 1966; the oximes described inCarroll et al. British Pat. 623,448; nitron; nitroindazoles; themercaptotetrazoles described in Kendal et al., US. Pat. 2,403,927 issuedJuly 16, 1946; Kennard et al., US. Pat. 3,266,897 issued Aug. 16, 1966and Luckey et al., U.S. Pat. 3,397,987 issued Aug. 20, 1966; thepolyvalent metal salts described in Jones US. Pat. 2,839,405 issued June17, 1958; the thiuronium salts described in Herz et al., US. Pat.3,220,839 issued Nov. 30, 1965; the palladium, platinum and gold saltsdescribed in Trivelli et al., US. Pat. 2,566,263 issued Aug. 28, 1951and YutZy et al., US. Pat. 2,597,915 issued May 27, 1952.

The photographic elements of this invention can contain incorporateddeveloping agents such as hydroquinones, catechols, aminophenols3-pyrazolidones, ascorbic acid and its derivatives, reductones andphenylene diamines. Combinations of developing agents can be employed inthe practice of the invention. The developing agents can be in a silverhalide emulsion and/ or in another suitable location in the photographicelement. The developing agents can be added from suitable solvents or inthe form of dispersions as described in Yackel US. Pat. 2,592,368 issuedApr. 8, 1952 and Dunn et al., French Pat. 1,505,778.

The photographic and other hardenable layers used in the practice ofthis invention can be hardened by various organic or inorganichardeners, alone or in combination, such as the aldehydes, and blockedaldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonateesters, sulfonyl halides and vinyl sulfonyl ethers, active halogencompounds, epoxy compounds, aziridines, active olefins, isocyanates,carbodiimides, miXed function hardeners and polymeric hardeners such asoxidized polysaccharides like dialdehyde starch and oxyguar gum and thelike.

The photographic emulsions and elements described in the practice ofthis invention can contain various colloids alone or in combination asvehicles, binding agents and various layers. Suitable hydrophilicmaterials include both naturally-occurring substances such as proteins,for eX- ample, gelatin, gelatin derivatives, cellulose derivatives,polysaccharides such as dextran, gum arabic and the like; and syntheticpolymeric substances such as water soluble polyvinyl compounds likepoly(vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers and other layers of aphotographic element employed in the practice of this invention can alsocontain alone or in combination with hydrophilic, water permeablecolloids, other synthetic polymeric compounds such as dispersed vinylcompounds such as in latex form and particularly those which increasethe dimensional stability of the photographic materials. Suitablesynthetic polymers include those described, for example, in Nottorf U.S.Pat. 3,142,568, issued July 28, 1964; White U.S. Pat. 3,193,386, issuedJuly 6, 1965; Houck et al., U.S. Pat. 3,062,674, issued Nov. 6, 1962;Houck et al., U.S. Pat. 3,220,844 issued Nov. 30, 1965; Ream et al.,U.S. Pat. 3,287,289 issued Nov. 22, 1966; and Dykstra U.S. Pat.3,411,911 issued Nov. 19, 1968; particularly eifective are thosewater-insoluble polymers of alkyl acrylates and methacrylates, acrylicacid, sulfoalkyl acrylates or methacrylates, those which havecross-linking sites which facilitate hardening or curing, those havingrecurring sulfobetaine units as described in Dykstra Canadian Pat.774,054.

The photographic elements used with this invention can containantistatic or conducting layers, such layers can comprise soluble salts,e.g. chlorides, nitrates, etc., evaporated metal layers, ionic polymerssuch as those described in Minsk U.S. Pat. 2,861,056 issued Nov. 18,1958 and Sterman et al., U.S. Pat. 3,206,312 issued Sept. 14, 1965 orinsoluble inorganic salts such as those described in Trevoy U.S. Pat.3,428,451 issued Feb. 18, 1969.

In addition, the photographic layers and other layers of a photographicelement employed and described herein can be coated on a Wide variety ofsup orts. Typical supports include cellulose nitrate film, celluloseester film, poly(vinyl acetal) film, polystyrene film, poly(ethyleneterephthalate) film, polycarbonate film and related films or resinousmaterials, as well as glass, paper, metal and the like. Typcially, aflexible support is employed, especially a paper support, which can bepartially acetylated or coated with baryta and/or an alpha-olefinpolymer, particularly a polymer of an alpha-olefin containing 2 tocarbon atoms such as polyethylene, polypropylene, ethylene butenecopolymers and the like and on one or both sides.

The photographic layers employed in the practice of this invention cancontain plasticizers and lubricants such as polyalcohols, e.g. glycerinand diols of the type described in Milton et al., U.S. Pat. 2,960,404issued Nov. 1, 1966; fatty acids or esters such as those described inRobijns U.S. Pat. 2,588,765 issued Mar. 11, 1952 and Duane U.S. Pat.3,121,060 issued Feb. 11, 1964; and silicone resins such as thosedescribed in Du Pont British Pat. 955,061.

It is also advantageous in the practice of this invention to provide thephotographic layers with surfactants such as saponin; anionic compoundssuch as the alkyl aryl sulfonates described in Baldsiefen U.S. Pat.2,600,831 issued June 17, 1962; amphoteric compounds such as thosedescribed in Ben-Ezra U.S. Pat. 3,133,816 issued 10 May 19, 1964; andwater soluble adducts of glycidol and an alkyl phenol such as thosedescribed in Olin Mathieson British Pat. 1,022,878.

The photographic elements employed in the practice of this invention maycontain matting agents such as starch, titanium dioxide, zinc oxide,silica, polymeric beads including beads of the type described in Jelleyet al., U.S. Pat. 2,992,101 issued July 11, 1961 and Lynn U.S. Pat.2,701,245 issued Feb. 1, 1955.

The photographic elements used in this invention can contain brighteningagents including stilbenes, triazines, oxazoles and coumarin brighteningagents. Water soluble brightening agents can be used such as thosedescribed in Albers et al., German Pat. 972,067 and McFall et al., U.S.Pat. 2,933,390 issued Apr. 19, 1960 or dispersions of brighteners may beused such as those described in Jansen German Pat. 1,150,274, Oetiker etal., U.S. Pat. 3,406,070 issued Oct. 15, 1968 and Heidke French Pat.1,530,244 and VanCampen U.S. Pat. 3,416,923 issued Dec. 17, 1968.

The various layers, including the photographic layers, employed in thepractice of this invention can contain light absorbing materials andfilter dyes such as those described in Sawdey U.S. Pat. 3,252,921 issuedMay 31, 1966; Gaspar U.S. Pat. 2,274,782 issued Mar. 3, 1942;Silberstein et al., U.S. Pat. 2,527,583 issued Oct. 31, 1950 andVanCampen U.S. Pat. 2,956,879 issued Oct. 18, 1960. If desired, the dyescan be mordanted, for example, as described in Jones et al., U.S. Pat.3,282,699 issued Nov. 1, 1966.

The sensitizing dyes and other addenda used in the practice of thisinvention may be added from Water solutions or suitable organic solventsolutions can be used. The compounds can be added using variousprocedures including those described in Collins et al., U.S. Pat.2,912,343 issued Nov. 10, 1959; McCrossen et al., U.S. Pat. 3,342,605issued Sept. 19, 1967; Audran U.S. Pat. 2,996,287 issued Aug. 15, 1961and Johnson et al., U.S. Pat. 3,425,835 issued Feb. 4, 1969.

The photographic layers used in the practice of this invention can becoated by various coating procedures including dip coating, air knifecoating, curtain coating, or extrusion coating using hoppers of the typedescribed in Beguin U.S. Pat. 2,681,294 issued June 15, 1954. Ifdesired, two or more layers can be coated simultaneously by theprocedures described in Russell U.S. Pat. 2,761,791 issued Sept 4, 1956and Wynn British Pat. 837,095.

As fully disclosed above and in a preferred embodiment this inventioncan be used with elements designed for color photography, for example,elements containing color-forming couplers such as those described inFrohlich et al., U.S. Pat. 2,376,679 issued May 22, 1945; Jelley et al.,U.S. Pat. 2,322,027 issued June 15, 1943; Fierke et al., U.S. Pat.2,801,171 issued July 30, 1957; Godowsky U.S. Pat. 2,698,794 issued Jan.4, 1955; Barr et al., U.S. Pat. 3,227,554 issued Jan. 4, 1966; andGraham et al., U.S. Pat. 3,046,129 issued July 24, 1962; or elements tobe developed in solutions containing color-forming couplers such asthose described in Mannes et al., U.S. Pat. 2,252,718 issued Aug. 19,1941; Carroll et al., U.S. Pat. 2,592,243 issued Apr. 18, 1952; andSchwan et al., U.S. Pat. 2,950,970 issued Aug. 30, 1966; and infalse-sensitized color materials such as those described in Hanson U.S.Pat. 2,763,549 issued Sept. 18, 1956.

In addition to the developing processes set forth in the examples, thehalide conversion-silver halide grains and elements containing themaccording to this invention can be processed by various methodsincluding processing in alkaline solutions containing conventionaldeveloping agents such as hydroquinones, catechols, aminophenols,3-pyrazolidones, phenylenediamines, ascorbic acid derivatives,hydroxylamines, hydrazines, reductones and the like.

Similar good results are obtained in the practice of this invention whenthe photographic material is a multicolor paper and is processed in thefive solution photo- 1 1 graphic development process commerciallyavailable by its trademarked name as Eastman Kodak Ektaprint C inaddition to the three solution bleach and fix development processdescribed herein.

The improvements in color balance, pre-process keeping, and post-processstability of photographic elements by controlling the characteristicdensity curve shape of the silver halide grains, by the addition of thecarboxysubstituted thiazolines or thiazolidines described herein, isfurther illustrated by the following examples of certain preferredembodiments of my invention.

EXAMPLE I Several multilayer, multicolor photographic papers areprepared having the following structure borne by a paper support,resin-coated on both sides. The resin is the rcpoly-olefin,polyethylene. Over the support, the first layer, comprises silverchlorobromide at a coverage of 50 mg./ ft. gelatin at a coverage of 200mg./ft. and a yellow dye forming coupler in a concentration of 150mg./ft. The ratio of chloride ions to bromide ions is 12:88. Aninterlayer of gelatin is coated at 100 mg./ft. over the yellow layer.The third layer is a magenta layer having a silver chlorobromidecoverage of 44 mg./ft. gelatin of 200 mg./ft. and a magenta dye formingcoupler of 55 mg./ft. The chloride to bromide ratio is 15:85. Aninterlayer is coated next containing an ultraviolet absorber in aconcentration of 67 mg./ft. and gelatin at a coverage of 200 mg./ft.Next a cyan layer is coated having a cyan dye forming coupler in aconcentration of 35 mg./ ft. gelatin at a coverage of 157 mg./ft. andsilver chlorobromide coverage of 35 mg./ft. the ratio of chloride tobromide being 15:85. An overcoat of gelatin is coated over the cyanlayer in a coverage of 100 mg./ft. These silver chlorobromide emulsionscontain the convertedhalide silver halide grains formed as describedmore fully in Davey and Knott US. Pat. 2,592,250 issued Apr. 8, 1952 andhave a solubility less than about 0.02 grams (silver citrate) andpreferably a solubility less than about 0.00002 gram (silverthiocyanate) per 100 ml. of water at C. These grains in the yellow layerare only blue sensitive and more than 10 times the blue sensitivity ofthe red and green sensitive layers, i.e. the cyan and magenta layers.

One coating is made having the above composition and containing 170mg./mole of silver of benzothiazole methiodide a known antifoggant andemulsion stabilizer shown as compound II. A second coating prepared fromthe above composition containing 200 mg./mole silver in the magentalayer of 4-carboxymethyl-4-thiazoline- 2-thione, shown as compound I.

A third coating is identical to the second but contains no additionalcompounds in the magenta layer.

Samples of each coating are exposed on an Eastman 1B sensitometer andprocessed using an 85 F. three solution process described in US. patentapplication Ser. No. 736,010 filed June 11, 1968 by Edens and Van Campenin which the following times are employed: development 3 /2 minutes,bleach and fix 1 minute, wash 2 minutes and stabilize 1 minute.

The sensitometric results are as follows:

TABLE 11 Coating and compound AD AD II 0.00 0.00 I 0. 10 0.0-t

Table I I shows that there is no difference in toe shape of the curve ofthe coating containing compound II and the coating not containing anyadditional compound. The coating containing compound I, as shown by thenegative measurements, has a sharper toe than either of the othercoatings in its characteristic curve shape as represented by curveintersects of a 0.3 and 0.5 negative shift in log E.

The significance of the measurements of Table II is explained by notingthat the green curve which resulted from the coating containing compoundII in its magenta layer has a softer toe than does the green curve whichresults from the coating containing compound I in its magenta layer. Thesofter toe of the green curve of the comparison coating tends to shiftthe color balance of highlight areas (such as clouds and whitebackgrounds) toward a reddish pink, which is undesirable. Sharpening thetoe, as accomplished by the addition of compound I to the magenta layer,results in whiter whites and more acceptable color balanced highlights.

EXAMPLE II In order to demonstrate the unexpected stability of themagenta layer when the curve shape stabilizing addendum is added, testsare conducted on incubation and compared to the fresh coatings. Theseshow (1) no toe softening, employing the addenda of this invention, (2)a shift in color balance accompanied by softening of the toe and shownby the positive values in the following table.

Samples of the coatings from Example I are subjected to the keepingconditions of 120 F. and a relative humidity of 50% for a period of 7days. Additional samples are kept refrigerated at a temperature of 40 F.and 50% RH. for the 7 day period.

Samples of these refrigerated and incubated coatings are exposed on anEastman 1B Sensitometer and processed as in Example I in which thesolutions are kept at a temperature of F. The time of development is 6minutes.

Table III shows the toe density differences of these coatings whencompared at a negative log E shift of 0.3 and 0.5 using the techniquedescribed in Example I.

1 Shows softened too. 2 Stable.

TABLE I Blue Green 1 Coating Rbd with Relative Relative Relativecompound speed ruin- Dim. spccd min- Dmx. p d Dina. Dim.

1 Compared at a reflection density of 1.0.

This Table I shows that no loss of relative speed occurs when using thecurve-shape control addenda of this EXAMPLE III In order to demonstratepost processing dye stability invention. Neither is there any adversechanges in density. 7 5 and pre-processing keeping, two coated samplesare pre- 13 pared having the same layer structure as in Example I. Themagenta layer of one coating contains 170 mg. of compound II/mole silverwhile the second coating contains 150 rug/mole silver of the curve-shapestabilizing addenda used in the practice of this invention.

Samples of these two coatings are tested for keeping stability for aperiod of 24 weeks. One set, a control set, is kept refrigerated at atemperature of 40 F. and 50% RH. The test set is kept at roomtemperature (78 F.) and a relative humidity of 50%.

Samples of these refrigerated and incubated coatings are exposed on anEastman 1B Sensitiometer and processed in the three solution process asdescribed in Example I.

1 Calculated at a reflection density of 1.0.

Stability is easily demonstrated in comparing the 45% speed increase inthe blue and 23% increase in the green of compound II with therefrigerated control. In sharp contrast, the addenda used in practicingthis invention exhibits only a speed increase in the blue and a 12%speed increase in the green layers.

EXAMPLE IV In order to demonstrate the unexpected results obtained bythe carboxy-substituted thiazolinethione addition to converted-halidesilver halide grains and to elements containing said grains, asubstantial number of compounds of similar structure and those havingknown emulsion and grain stabilizing effects are combined in multilayer,green light-sensitive coatings. While some insignificant negativedensity differences at the log E shifts are noted, only the addition ofcompound I provides a desirable color balance.

While the range of effectiveness of this stabilizing addenda varies fromabout 50 to about 500 mg./mole of silver, a preferred range whichproduces outstanding results is from about 100 to about 300 mg./molesilver.

Several two-layer green, light-sensitive photographic coatings areprepared consisting of a magenta layer which is coated on a polyethyleneresin coated paper support having a gelatin protective layer coated overthe magenta layer.

Samples of these coatings are exposed on an Eastman lB Sensitometer andprocessed by the method described in Example I. Toe density differencesare compared at a negative log E shift AD of 0.3 and 0.5 using thetechnique described in Example I.

14 tration of 55 mg./ft. and a converted-halide silver chlorobromideconcentration of 50 m,g./ft. with a chloride: bromide ratio of 15:85.Over this is coated a gelatin overcoat of 100 mg./ft.

Samples of the coatings of this example are exposed to green light on anEastman 1B sensitometer and processed by the method described in ExampleI. Table VI compares the maximum and minimum densities of the coatingscontaining a curve shape inhibiting compound with a coating notcontaining said inhibitor. Table VI, further compares toe densitydifferences at a negative log E shift of 0.3 and 0.5 using the techniquedescribed in Example I.

TABLE VI Coating and compound Dmln S in :s

R2 NR Compound R1 R2 R:

I H -CH2COOH -H XIII..-" -(OI I2)2N- OH: CH: C OOH S s C O OH XIV-CH:4COOH CH3 -OOOH /S E& H R4 HO O O N-Ro H -H 1-I -(CH2)5CH3 'CH2l C OOH -CH +0113 The significance of the measurements of Table VI can beexplained by noting that all the above listed compounds sharpened thetoe (indicated by negative numbers) at a 0.3 negative log E shift whencompared to the coating not containing a fog inhibiting compound.

TABLE V Level Compound (gJmole) Dunn mnx. M ILfi4-carboxymethyl-4-thiaz0line-2-thione 0. 20 0. 12 2. 6O -0. 07 -0. 04Benzothiazole methiodide O. 17 0. 10 2. 491,15-dibr0mo-3,5,11,13-1;exti-axo-6 oxa-4,10, riazopcntadecane 5. ()00.12 2. 50 0. 02 0. 02 6,7-dihydro-2-methylfiH-eyclopenta-pyrimidine-4-(1H)-thione O. 20 0. ll 2. 50 0.00 +0. 02"-B romo-N-butylcaproamide. 3. 00 0. 12 2. 48 0. 03 0. 034-bromo-N-oetylbutyramide. 3. 00 0. 11 2. 46 -0. 01 O. 02 3-{BN,N-dimethylearboxamidoethylthiol4-phenyl-1,2,4'thiaz 0. 20 0. 11 2. 18+0. 03 +0. 05 4-Ionnyl-4-thiazoline2-thi0ne oxime 0. 20 0. 12 2. 42 0.00 0. 0O 4-propionyloxymethylt-thiazoline-Z-thione 0. 20 0. 12 2. 50 +0.04 +0. 063-(l-carboxy-3-methylthiopropyl)-4-methyl-4-thiazoline-2-thione- 6.000.11 0.17 No curve l-acetyHi,5-dimethyl-2-thiohydant0in 0. 20 0. 12 2.50 +0. 02 0. 00 1-aeetyl-5-ethyl-5-methyl-Z-thiohydantoin 0. 20 0. 11 2.51 0. 00 +0. 02

EXAMPLE V EXAMPLE VI In order to demonstrate the effectiveness ofcertain other carboxy substituted thiazolinethione and thiazolidines setforth below a series of two layers, green, light sensitive photographiccoatings supported on a resincoated paper are prepared having a gelcoverage of 200 Several multicolor, multilayer photographic materialsare prepared according to the general structure described in Example I.

Separate coatings are prepared as described above conmg./ft. a magentadye forming coupler in a concen- 5 taining their magenta layer 200 mg.of compound I per silver mole; 200 mg. of compound XVII per mole ofsilver; and 200 mg. of compound XV per mole of silver.

Samples of these coatings are exposed on an Eastman 1B sensitiometer andprocessed by the procedure described in Example I.

Table VII further compares the coatings of this example with a coatingcontaining compound H in an amount of 170 milligrams per mole of silverin its magenta layer, the coating described in Example I not containingany additional compound in its magenta layer. The comparisons of TableVII record toe density differences at a negative log E shift of 0.3 and0.5 using the technique described in Example I.

These results indicate that compounds I, XVII and XV sharpened the toe(indicated by the negative numbers) at both negative log E shifts of 0.3and 0.5.

The invention has been described in detail with particular reference topreferred embodiments thereof but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

I claim:

1. A photographic element comprising a support having coated thereon atleast three superimposed hydrophilic colloid layers, one of said layerscomprising a coupler capable of forming a yellow dye upon colordevelopment and surface sensitized converted halide silver halide grainssensitive to blue radiation; another of said layers comprising a couplercapable of forming a cyan dye upon color development and surfacesensitized converted-halide silver halide grains sensitive to redradiation; and another of said layers comprising a coupler capable offorming a magenta dye upon color development, surface sensitizedconverted-halide silver halide grains sensitive to green radiation andfrom about 100 to about 300 mg./mole of silver of a carboxy substitutedcompound selected from the group consisting of (I) s r H S Raf Ts a 01'l :ai N-R, 11000- N-R in which R is hydrogen, carboxymethyl or each R isalkyl when R is other than hydrogen or is carboxymethyl and each R and Rare each hydrogen or acyl, R is hydrogen or methyl and R is hydrogen,carboxyl or lower alkyl, provided at least one of R or R iscarboxymethyl; the halide in said converted-halide silver halide grainsconsisting of at least 50 mole percent bromide, up to 10 mole percentiodide and any remaining halide being chloride; whereby sharpness ismaintained in the toe area of the characteristic D log E curve.

2. The element of claim 1 wherein the hydrophilic colloid is gelatin.

3. The element of claim 1 wherein the carboxy substituted compound is4-carboxymethyl-4-thiazoline-2- thione.

4. The element of claim 1 wherein the support is a white reflectingsupport.

*5. The element of claim 1 wherein the red-sensitive layer containingthe cyan-forming coupler is the outermost light sensitive layer.

6. The element of claim 1 wherein the blue-sensitive layer is disposedadjacent the support.

7. The element of claim 1 wherein the cyan colorforming coupler is aphenolic compound.

8. The element of claim 1 wherein the magenta colorforming coupler is apyrazolone.

9. The element of claim 1 wherein the converted-halide silver halidegrains are surface sensitized by a sensitizer selected from the groupconsisting of sulfur, selenium and tellurium.

10. A photographic element comprising a white reflecting support havingcoated thereon at least three superimposed gelatin layers, the layeradjacent the white reflecting support comprising a coupler capable offorming a yellow dye upon color development and sulfur, selenium ortellurium surface sensitized converted-halide silver halide grainssensitive to blue radiation; an outermost light sensitive layercomprising a phenolic coupler capable of forming a cyan dye upon colordevelopment and sulfur, selenium or tellurium surface sensitizedconverted-halide silver halide grains sensitive to red radiation; andanother layer comprising a pyrazolone coupler capable of forming amagenta dye upon color development, sulfur, selenium or telluriumsurface sensitized converted-halide silver halide grains sensitive togreen radiation and from about to about 300 mg./mole of silver of4-carboxymethyl-4-thiazoline-2-thione; the halide in saidconverted-halide silver halide grains consisting of at least 50 molepercent bromide, up to 10 mole percent iodide and any remaining halidebeing chloride; whereby sharpness is maintained in the toe area of thecharacteristic D log E curve.

References Cited UNITED STATES PATENTS 2,860,976 11/1958 Spath 961093,565,625 2/ 1971 Scavron 96--109 3,556,799 1/1971 Yamamoto et al. 96-56X 2,403,721 7/1946 Jelley et a1. 96-74 X 2,956,876 10/l960 Spath 96563,582,333 6/1971 Yost et al. 9674 NORMAN G. TORCHIN, Primary Examiner W.H. LOUIE, JR., Assistant Examiner US. Cl. X.R.

